A constant concern in the field of commonly-used chairs and armchairs for automobiles is that of obtaining designs for backrests and seats which allow the backrest to reach a reclined position while at the same time offering support to the lumbar region of the user, thereby providing a comfortable and safe position for a user's body while preventing positional bad habits and the possibility of traumatism to a user's spine in the case of an accident.
The automotive sector has provided reclining seats with lumbar support, due to the production of new and innovative ergonomic designs, related to the comfort and safety needs of the users of automobiles. These designs include mechanisms which combine several ergonomic factors such as:
a) positioning the seat in relation to the steering-wheel or the vehicle's dashboard. PA1 b) allowing for changeable positions which may be maintained between the elements of the seat-frame, seat and backrest, in order to provide a reclined position, and PA1 c) designing the parts of the seat, such as the seat-covers, filling material and solid support elements seat-frame, so as to comfortably situate the body and the forms of the backrest in order to provide lumbar support to the user's spine. PA1 a) providing positioning levers which activate wire pulleys or cables which release or halt the sliding of the whole seat on parallel rails, governing the horizontal position of the seat, PA1 b) providing positioning levers which activate wire pulleys or cables which release or maintain the vertical position of the backrests to allow the entrance or exit of passengers to and from the back seat of the vehicle, PA1 c) adjusting the reclined position in the corresponding vertical position, erect position, of the backrest, by means of positioning levers which when activated or immobilized, allow a variety of reclined positions for the backrest body which pivots on two fixed parallel positions which support the sides of the seat frame. These adjustments may also be achieved by means of a screw mechanism which gradually adjusts the reclined position of the backrest which pivots on two parallel supports placed on the sides of the seat. PA1 a) it can be manufactured at a lower cost, as the device is made from pieces of stamped steel and the two springs are made from an elastic material with high torsional resistance. PA1 b) the device is activated immediately when a user leans back on it; PA1 c) when activating the device, two benefits are simultaneously provided; the ability to recline and lumbar support; PA1 d) the device requires less maintenance; PA1 e) due to the smaller number of pieces it is very easy to manufacture and assemble the device, and the number of operating faults and maintenance measures is reduced.
The simultaneous consideration of these ergonomic design factors, has produced mechanisms ranging from the very simple to the most sophisticated with the aim of combining them and obtaining the best possible results. As a result, most of the existing mechanisms are based on the following basic general principles:
All the above mechanisms suffer from problems. For example, it is very common for the lever and pulley system to get stuck or break. If this happens the backrest can be released and deformed, so that a user's spine does not have the necessary lumbar support which would provide it with stability and safety in the event of an accident suffered by the vehicle due to improper driving.